Bioavailability of proteins from beans usually consumed (Phaseolus vulgaris) by innovative methods using stable isotopes in adults and older people

Abstract

The quality of protein ingested plays an important role in nutritional needs throughout life, especially in developing countries and in particular during pregnancy, early childhood, and aging. Uncertainty about diet quality, specifically with reference to protein quality, has potential impacts on a nation's health, economy, agriculture, and food security. Estimates of protein digestibility (bioavailability) based on analysis of ileal effluent and faeces do not represent the quality of absorbed amino acids. Ideally, the bioavailability of amino acids should be measured by methods that evaluate the difference between consumed amino acids and the absorbed amino acids. However, the absorption of amino acids is practically non-measurably noninvasively in healthy humans. The use of plant protein intrinsically labeled by stable isotope offers an innovative solution to this problem. Deuterated water (2H2O) is suitable for intrinsically labeling plant proteins such as beans. The labeled amino acids present are ingested in the test meal and incorporated into the body, representing a single measure of bioavailability. This study aims to develop, implement and apply a new methodology, using stable isotopes, for the evaluation of protein bioavailability, using as an example the bean, a food of great importance in food in general, by means of the stable isotope technique using deuterium. The project will be divided into two parts: one for agriculture and the other for human nutrition. Planting/harvesting of Phaseolus vulgaris L. beans will be performed. After two weeks of flowering, deuterated water will be added to the bean planting, which will then be dried. Bromatological analyzes and the evaluation of the incorporation of deuterium in beans will be carried out. Concomitant to bean cultivation, a pilot protein absorption test will be done with 15 healthy volunteers to validate the methods. For comparison purposes, the deuterium-labeled milk protein (high absorption) and deuterium-labeled bean (test meal) will be used as markers. Volunteers will consume the test meal. Blood and urine samples will be taken at baseline (before meal) and every hour, up to eight hours after the meal. Subsequently, the second experiment on nutrition and human health will be carried out; the beans produced in the unmarked agriculture experiment will be given to elderly volunteers residing in a long-term institution with a bean preparation commonly consumed by Brazilians (soaked for four hours after being cooked under pressure) for two weeks. At the end of the second week, the bioavailability measurement experiment will be carried out, with the bean offered, and the biological samples will be collected with the best results obtained in the first nutrition experiment. Samples will be analyzed by isotopic ratio mass spectrometry. It is expected that this methodology may promote a better understanding of the absorption of proteins and amino acids, using less invasive and employable methods with different foods and in different age groups and clinical conditions. This work will have an important impact on the general population as well as for farmers, health workers, nutritionists, nurses, and doctors. (AU)